1. Field of the Invention
The present invention generally relates to the manufacture of electronic circuit boards, and, in particular, to a method and apparatus for transferring heat during a wave solder technique.
2. Background of Invention
Wave solder is a common method of connecting multiple electronic components or connectors to a circuit board using a wave of molten solder. A circuit board populated with pin-in-hole (PIH) electronic components or connectors is passed over a wave of molten solder. The molten solder wets the leads of the components and fills the plated-thru-holes (PTH) of the circuit board.
Typical wave solder techniques may suffer from a problem referred to as the ‘leading edge’ effect. The leading edge effect may be experienced when the PIH components at a leading edge of the circuit board experience higher hole fill defects than the PIH components at a trailing edge of the circuit board. The leading edge of the circuit board is the edge that contacts the wave of molten solder first, and the trailing edge is the edge that contacts the wave of molten solder last. The leading edge effect may be caused by a temperature differential between the PIH components at the leading edge of the circuit board versus the PIH components at the trailing edge of the circuit board. The temperature differential may be explained by a pre-heating effect experienced by the PIH components at the trailing edge of the circuit board. During a wave soldering technique heat may transfer from the leading edge of the circuit board to the trailing edge of the circuit board via a power plane or a ground plane, and in turn pre-heat the PIH components at the trailing edge of the circuit board. The pre-heating heating effect witnessed by the PIH components at the trailing edge of the circuit board may be responsible for the difference in hole fill defects between PIH components at the leading edge of the circuit board versus the trailing edge of the circuit board.
Therefore, pre-heating the PIH components at the leading edge of the circuit board to minimize or eliminate unwanted hole fill defects may, among other things, be desirable.